The present invention relates to drive systems for automatic clothes washers, and more particularly to improvements in a planetary gear drive system for a vertical axis washer.
In an automatic washer, drive systems are utilized for drivingly interconnecting a motor with a perforate wash basket acting as a clothes receiving receptacle and an agitator disposed within the wash basket. Automatic washers may be afforded with a direct drive system between a reversible motor and the agitator/wash basket so that the washer will be able to selectively operate in a "agitate" mode, wherein the agitator is oscillated while the basket is held stationary, and in a water extraction or "spin" mode, wherein the agitator and basket are spun together. Typically, the drive system includes a clutch mechanism to selectively operate between the "agitate" mode and the "spin" mode.
In the "agitate" mode, the motor is in a reversing drive mode wherein drive is established to the agitator at a rate of rotation much reduced over the rate of rotation of the motor. The drive system may further include therefore, a gear reduction mechanism such as a planetary gear arrangement.
Previously known drive systems including planetary gear arrangements are complicated mechanisms, requiring metallic components and precisely machined mating surfaces. For example, U.S. Pat. No. 4,317,343, discloses a drive system including a planetary gear arrangement in an automatic washer. This reference teaches the use of a metallic gear casing surrounding a metallic carrier assembly having an upper frame and a lower plate and axle pins supporting stepped pinion gears. In this configuration, in order to properly orientate the stepped pinion gears and to ensure that the axle pins are securely fixed to the carrier assembly, the upper frame and lower plate portions of the carrier assembly must be precisely machined. In particular, fabricating the holes in the upper frame into which the axle pins are inserted require a high degree of precision machining.
Commonly assigned U.S. Pat. No. 4,969,341 also discloses a drive system for an automatic washer. Included in the disclosed drive system is a gear reduction mechanism or planetary gear arrangement. This reference, however, also teaches the use of a metallic carrier plate and a plurality of metallic axle pins for supporting a plurality of planet gears. As discussed above, this configuration of a planetary gear arrangement requires precision machined parts which are relatively very costly. Furthermore, U.S. Pat. No. 4,969,341 also teaches the use of a combination of thermoplastic parts and metallic parts in the construction of the planetary gear arrangement. This use of dissimilar materials for the components in the planetary gear arrangement results in differing thermal expansion characteristics between the planetary gear components. This difference in thermal expansion may result in excessive spacing between components at elevated temperatures such that the performance of the planetary gear arrangement is degraded.
It would therefore be an improvement in the art if a less expensive planetary gear arrangement was provided which did not require costly high precision machining operations. Further, it would also be highly desirable to overcome the problems of differentials in the thermal expansion of various gear components.